A client with bipolar disorder begins taking lithium carbonate, 300 mg four times a day. After 3 days of therapy, the client says, "My hands are shaking." The best response by the nurse is which of the following?

Choice A reason: Fine motor tremors are a common early side effect of lithium, affecting cerebellar function due to its narrow therapeutic index and sodium channel interactions. These typically subside within weeks as the body adjusts to stable serum levels (0.5–1.2 mEq/L), making this an accurate, reassuring response. Choice B reason: Dismissing tremors as unimportant unless persistent for a month is incorrect. Lithium tremors, linked to cerebellar effects, often resolve sooner, but persistent tremors may indicate toxicity (levels >1.5 mEq/L), risking neurological damage. This response delays necessary monitoring, ignoring the drug’s neuropharmacological impact. Choice C reason: Acknowledging tremors but implying the client’s concern is excessive is dismissive. Tremors result from lithium’s cerebellar effects, a legitimate side effect. This response fails to educate about the expected resolution timeline or need for monitoring, risking patient distrust and ignoring the drug’s neurobiological effects. Choice D reason: Labeling tremors as a potential toxicity sign is misleading, as early fine tremors are typically benign, not indicative of toxicity (>1.5 mEq/L), which involves severe symptoms like confusion. This overstates risk, causing unnecessary alarm, and does not address the common, transient cerebellar effect of lithium.